1. Field of the Invention
The present invention relates to the field of optical chemical detection of analytes. More particularly, the present invention provides a device wherein the electromagnetic radiation generator provides a substrate for chemical sensors, and wherein the spectroscopic properties of the chemical sensor are modified upon contacting an analyte. The present invention also provides a method for the selective and simultaneous detection and quantitation of analytes, and a method of making the device.
2. Description of the Related Art
Chemical sensors are widely used in clinical diagnosis and biomedical research to selectively detect the presence of a particular analyte or ensemble of analytes, or to measure other characteristics of samples, such as pH. These measurements are based on the principle that interaction of a chemical sensor with an analyte within a sample results in modification of spectroscopic properties of the sensor to a degree that depends on the concentration of the analyte. The modification of spectroscopic properties may involve changes in the intensity, wavelength, phase, or polarization of the incident electromagnetic radiation. For example, fluorophores are molecules that absorb light at certain wavelengths and emit light of a different wavelength (generally longer). In the presence of an analyte, the optical properties of some fluorophores are altered and this forms the basis for optical detection and quantitation of analytes using fluorophores.
Many devices disclosed previously use one or more fiber optic strands having a chemical sensor or sensor element at its tip. Some devices use an array of optical fibers to detect the presence of a substance in a sample. One such array disclosed in U.S. Pat. No. 5,320,814 has two discrete optic array ends, each of which is formed of multiple end faces of the optical fibers. On one of the optic array ends is a light energy absorbing dye disposed as an uninterrupted deposit in aligned organization upon the end faces.
Another optic sensor is disclosed in U.S. Pat. No. 5,512,490 (""490). The device comprises a supporting member and an array formed of heterogeneous semi-selective thin films which function as sensing receptor units and are able to detect a variety of different analytes and ligands using spectral recognition patterns. The supporting member may be a xe2x80x9csupporting substratexe2x80x9d which is a translucent or transparent article such that light energy may pass through without being substantially altered or hindered. As shown in FIG. 2 of the ""490 patent, the receptor units are formed on the supporting substrate and white light from a separate excitation source, such as an arc lamp, and a dichroic mirror are used to illuminate each receptor unit. Alternatively, the supporting member may be a collection of optical fibers, each of which is coated with a polymer/dye combination on a distal tip. As shown in FIG. 23 of the ""490 patent, light from a separate excitation source in combination with a dichroic mirror is introduced into the optical fibers to illuminate the polymer/dye combination.
These and other existing devices are expensive, and bulky. Furthermore, these devices require a large amount of energy to operate, in part because the excitation light source is separate from the chemical sensor/sensor element.
The present invention provides an electromagnetic radiation (ER)-based sensor device that is simple, easy to make and is compact compared to existing devices. While any ER generator may be used for the present invention, in a preferred embodiment, the ER generator is a modified LED (light emitting diode) having micro-wells on its surface. The individual micro-wells are filled with one or more chemical sensing materials so as to form a sensor array.
Thus, an object of the present invention is to provide an ER-based sensing device that is compact and energy efficient for detecting the presence of one or more analytes in samples.
Another object of the present invention is to provide an ER-based sensing device for the simultaneous detection and quantitation of one or more analytes in a sample.
Another object of the present invention is to provide a method for detecting the presence of one or more analytes in a sample.
Another object of the present invention is to provide a method for detecting and simultaneously quantitating one or more analytes in a sample
Yet another object of the present invention is to provide a method of making an ER sensor and sensor array for the detection and quantitation of one or more analytes in a sample.
A detecting device according to the present invention comprises an ER generating substrate having a chemical sensor for interacting selectively with a particular analyte in a sample. In the absence of the analyte, the chemical sensor displays certain baseline spectroscopic properties characteristic of the sensor. However, when the analyte is present in the sample, the spectroscopic properties of the chemical sensor are modified. Detection and quantitation of the analyte are based on a comparison of the modified properties and the baseline properties and the use of standard calibration methods that are well known to those skilled in the art of analytical chemistry.
The present invention also includes a method of making the detecting device. In the method of making the device according to the present invention, micro-wells are formed on an ER substrate and a chemical sensor and/or sensor element is placed therein in a suitable holding material.